Valve for vacuum-pumps.



No. 702,054. Patented lune l0, I902.

W. F. GAR BISUN. VALVE FDR VACUUM PUMPS.

(Application filed Feb. 7, 1961. I (N o M o d e l fiaineayew THE Nunms PETERS co. waYo-Lrmo \msumamu. n, c

UNITED STATES PATENT OF IC W'ILLIAM F. GARRISON, OF BROOKLYN, NEW.YORK, ASSIGNOR TO GUILD & GARR-ISON, OF BROOKLYN, NE\V YORK, A FIRM.

i VALVE FOR VACUUM-PUMPS.

SPECIFICATION forming part of Letters Patent No. 702,054, dated June 10, 1902.

Application filed February 7, 1.901- Serial No. 46 295- (No model.)

f all whom it may concern: V w Be it known that I, WILLIAM F. GARRISON,

a citizen of the United States, and a resident of y the borough of Brooklyn, in the city and State This invention relates to a valve of the slide type which serves the two purposes of an iri- IO let-valve and an outlet-valve,

The object of the im provement is to increase the efficiency of such a valve. 7

I will first describe my invention in detail with reference to the accompanying drawings r of a valve embodying my invention and will afterward point out itsnovelty in a claim.

' Figures 1 and 2 represent longitudinal sectional views of the valve audits chest and a part of the vacuum-cylinder to which they are applied.

Similar characters of reference designate corresponding parts in all the figures.

o. is the cylinder; 1), the workingpiston; c, the valve-chest d, the valve-seat; o, the slidevaly'e In the seat cl there are three portsviz., a central port 5, communicating with the inlet-pipe at f, and two ports 6, communicate ing with the cylinder, one at each end thereof. From the interior of the valve-chest c'there is an outlet at g. The valve has it in threepassagesviz. a central arch-shaped passage 7, which terminates in its face with two ports 8, andtwo separated passages 9, the latter passages, which extend right through the valve,

having ports 10 in its face at equal distances from the adjacent ports 8 and having' ports 11 in its back. The parts-12 of the valveface between its ports 8 are long enough to cover the ports 6, the central part 13 of the 40 valve-face is more than long enough to cover the central port 5 in the seat, and the valve ports 8 are longer than the seat-ports 6 and have their respective outer ends so far apart that whenthevalve is in its central position and the piston 19 at either end of its stroke, as shown in Fig. 1, there is a communication through the passages 7 and ports 6 between the two ends of the cylinder.- To the back of the so-constructed slide-valve U, at about the middle of its length, there is fixedly secured by a bolt 6 a crown h, to which there are hinged, at 1' two automatically-operating flap-val'vesj, each covering one of the ports 1.1. These valves j are normally closed by very light springs it, applied between their backs and bearingsconstituted by a flange 20 on the crown; but each is opened bythe pressure produced in the cylinder on its respectiveside of the piston in the movements ofthellatter. Between this flange 20 and the hinges there are shonldersil onthe said crown, which constitute stops to limit the opening movement of said valve. On each side of the crown it there is arranged lengthwise on the back of the valve 0 one of two straight parallel barsl, only one of which is shown, to

which are applied, betweenthem and the lugs 02 in the interior of the valve-chest, light springs m, which tend to hold the said bars with a light pressure upon portions of the back of the valve that are parallel with its face, but which permit the valve to rise and liberate any accidental accumulation of pressure in the cylinder. These bars Z are prevented from moving lengthwise by means of .75 stationary rods orpins 0, which pass through them'and are secured in the sides of the valve-chestgbut to permit the said bars'to 'movevertically, and, so permit the valve to rise from its seat-whenever necessary, the 20 .holes provided in the said bars for the rods or pins ojare elongated vertically. This valve 0) is intended ,toreceive such a positive and regular reciprocating motion as to be approximately at the middle of its stroke, as shown in Fig. 1, whenthe 'piston b is at either end of its stroke, the valve moving in the same wdirection inywhich the piston has been moving," or, in other words, the movement of the valve always following the movement of the piston in either direction. This movement may be given to the valve by any suitable meansas, for example,- by an eccentric on'the crank-shaft of an engine which drives piston b.

The operation is as follows: First, suppose the piston b to have just arrived at the righthand end of its stroke. The valve '0 will be moving to the right and at this instant will be at the middle of its stroke, the inlet-port 5 will be closed, and the seat-ports 6 will both we be slightly open to their corresponding valveports 8, so that there will be communication formed between the two ends of the cylinder through the valve-passage 7, and the piston will be for the moment in equil'ibm'o. As the valve continues its movement to the right it will gradually open the right-hand seat-port wide to its port 8 and will at the same time open its left-hand port 8 to the inlet-port and open its left-hand port 10 to the left-hand seat-port 6, as shown in Fig. 2, in which the piston is shown at the middle of its stroke and the valve as having completed its stroke to the right. The right-hand end of the cylinder is now freely open through the valvepassage 7 to the inlet-pipe f, while the lefthand end of the cylinder is open to the interior of the valve-chest and to the dischargeoutlet g through the left-hand valve-passage 9 and its port 11 and valve j, the closingspring 713 of which yields automatically to permit its opening by the pressure of the gas or vapor in front of the piston. By the time the piston b has arrived at the left-hand end of its stroke the slide-valve will have made half its return movement and so have again arrived at the central position, (shown in Fig. 1,) and the pressure will be balanced between the two ends oi the cylinder. Then the continued movement of the valve to the left will produce communications between the several valveports and seat-ports precisely the reverse of that hereinabove described with reference to the movement of the piston to the left-that is to say, the left-hand end of the cylinder will be opened through the ports 6 8, passage 7, and ports 5 to the inletf, and the right-hand end of the cylinder will be open through its port 6 and the right-hand valvepassage 9 and valve j to the valve-chest and the outlety.

It may be understood that the proportion and spacing of the ports 8 and 6 of the valve and seat, as herein described, to form communication between the cylinder ends prevent the retention in the clearance-space between the piston and either end of the cylinder at the termination of the pistons stroke of any air or gas which would have to expand at atmospheric pressure before any fresh air or gas could enter.

In the above-described operations the valves j might close automatically by the pressure within the valve-chest during the movements of the piston from their respective end of the cylinder; but the purpose of the spring la is to insure them a more prompt and, lively action.

What I claim as my invention is- In a vacuum-pump, the combination with a slide-valve in which are two separated passages extending through it for communication between the cylinder-ports and the discharge-outlet, valves hinged to the back of said slide valve for closing said passages, springs for closing said hinged valves, and a crown on the slide-valve forming bearings for said springs and stops to said hinged valves, substantially as herein described.

In testimony that I claim the foregoing as my invention I have signed my name, in presence of two witnesses, this 14th day of Jan 11- ary, 1901.

\VILLIAM F. GARRISON.

l/Vitn esses:

FREDK. HAYNES, LIDA M. EGBERT. 

